selecting many objects inside blender and export them as seperate .obj with one click?
certainly! but it's a little hacky.  Run this from text editor for a few objects selected. Make sure to change the folder to a valid path.

import bpy
import os

folder = '/home/zeffii/Uploads/'

selected = bpy.context.selected_objects.copy()
bpy.ops.object.select_all(action='DESELECT')

for obj in selected:
    name = obj.name.replace('.', '_')
    obj.select = True
    fullpath = os.path.join(folder, name + '.obj')
    bpy.ops.export_scene.obj(
        filepath=fullpath, 
        check_existing=True, 
        axis_forward='-Z', 
        axis_up='Y', 
        use_selection=True, 
        use_animation=False, 
        use_mesh_modifiers=True, 
        use_edges=True, 
        use_smooth_groups=False, 
        use_smooth_groups_bitflags=False, 
        use_normals=True, 
        use_uvs=True, 
        use_materials=True, 
        use_triangles=False, 
        use_nurbs=False, 
        use_vertex_groups=False, 
        use_blen_objects=True, 
        group_by_object=False, 
        group_by_material=False, 
        keep_vertex_order=False, 
        global_scale=1, 
        path_mode='AUTO')
    obj.select = False


Most of those options in export_scene are default and you can remove those lines, or comment them out, but some of them may be useful if you want to change them later.

There's a nice Template for this in (with a slightly different approach - as in, it checks to see if the destination is valid first, which is handy if you aren't too familiar with paths): 
TextEditor -> Templates -> Python -> Batch Export



update:

https://gist.github.com/zeffii/529d435d5853e92dcc51

I'm not entirely sure how to inherit all the properties from the original exporter operator for objs. I could add them individually if you need specific props, else it would be wasted effort adding them all.

With the exporter code, you navigate to select a folder, don't have to type any thing, just hit the Export selected Objects as obj button at the end.